Growing the Fastest Calendar SaaS to Thousands of Users

TL;DR: John Li and Mike met at Berkeley, built two companies before Vimcal, and came up with the calendar idea while struggling to schedule 30+ investor meetings per week during fundraising. They spent 6 months building the first version. They launched through the YC internal forum and grew through word-of-mouth. They borrowed a tactic from Superhuman: requiring a 30-minute onboarding call for every new user. From January 2020 to October 2021, they onboarded thousands of users this way. Significant signup upticks came from Twitter shoutouts. A daily tutorial email series doubled retention overnight.